About this nifty "Onion Pi" HOWTO just published at Adafruit, Phil Torrone says, "Limor and I cooked up this project for folks. We are donating a portion of any sales for the pack we sell that helps do this to the EFF and Tor."

Browse anonymously anywhere you go with the Onion Pi Tor proxy. This is fun weekend project that uses a Raspberry Pi, a USB WiFi adapter and Ethernet cable to create a small, low-power and portable privacy Pi. Using it is easy-as-pie. First, plug the Ethernet cable into any Internet provider in your home, work, hotel or conference/event. Next, power up the Pi with the micro USB cable to your laptop or to the wall adapter. The Pi will boot up and create a new secure wireless access point called Onion Pi. Connecting to that access point will automatically route any web browsing from your computer through the anonymizing Tor network.

No notable advantage over installing it on your computer with a properly configured firewall; but this arrangement should terminate the attempts of various always-running-in-the-background updaters and whatnot to attempt to phone home in incautious ways.

You can configure your computer’s firewall to do the same; but the easy-install Tor bundle only handles the browser it includes.

In that vein, it’s important to remember that whatever you are doing is visible to your Tor exit node(and people running exit nodes for the purposes of seeing what passes by isn’t unheard of). Keep that in mind.

From what little I know about Tor, it seems like there’s a lot of ways data can leak out whether that’s through unprotected apps, documents or other services. This would prevent that, which is especially important for those for whom a small configuration error could literally mean death.

Also, I wonder if this could be used to make a hidden anonymous network simply by plugging it in to a private office or government router – that would be pretty cool.

Tor is definitely a tool to be used with caution. I have the greatest respect for the Tor team, they are Pretty Serious; but the fundamental architecture can only protect you from certain things(and, indeed, might make you more vulnerable if you use it incorrectly).

The other issue(also more or less architectural and fundamental, not ‘you fools! What have you done?) is that Tor traffic looks abnormal. Very, very, weird. You can’t tell exactly what the target is up to, it’s a welter of TLS connections; but it’s instantly recognizable.

Against a mostly-free-but-surveillance-crazed state like the US, that’s fine. If a state were to ban Tor, period, though, hiding your activity would be much more demanding and difficult.

If you are using a closed source OS like MS windows, then there can you be sure your firewall is really protecting you from leaking personal information? A Tor router like Onion Pi or Anonobox FORCES all traffic through Tor including all DNS requests (at least Anonobox does), thus preventing your OS from betraying you.